The present invention relates to a holographic stereogram exposure apparatus, a method thereof, and a holographic stereogram generation system for exposing 3-D image information on a hologram recording medium.
To create a holographic stereogram, for example, a subject is photographed from different observation points to generate many images as original images. These images are sequentially recorded as strip-shaped or dot-shaped element holograms on a single holographic recording medium.
For example, FIG. 12 shows a holographic stereogram having parallax information in a horizontal direction only. A subject 100 is sequentially photographed crosswise from different observation points to generate a plurality of original images 101a to 101e. An image recording apparatus sequentially records these original images as element holograms in strips on a holographic recording medium 102, generating the holographic stereogram.
Image information is obtained by sequentially photographing from different observation points along a cross direction and is sequentially recorded crosswise as element holograms in strips. When an observer views this holographic stereogram with both eyes, right and left eyes accept slightly different 2-D images respectively. This causes the observer to feel parallax, reproducing a 3-D image.
Meanwhile, the hologram exposure is very sensitive to vibrations. During the exposure time, an optical system must not vibrate on a recording wavelength scale. As mentioned above, however, a holographic stereogram may be generated by exposing thin slit element holograms one by one. In this case, it is necessary to wait until a vibration attenuates between exposures to some extent. This has been a hindrance to shorten the time to generate holograms. Since only the inside of an element hologram is exposed, the other beams are discarded as unnecessary beams. After all, this increases the total exposure time and requires a costly, high-power laser, causing unfavorable effects.
The present invention has been made in consideration of the foregoing. It is therefore an object of the present invention to provide a holographic stereogram exposure apparatus, a method thereof, and a holographic stereogram generation system capable of shortening the time for generating holograms.
A holographic stereogram exposure apparatus according to the present invention exposes 3-D image information to a hologram recording medium, including: an object beam optical system which superposes and projects light beams passing through a plurality of images separately displayed in a parallax direction and then condenses these beams to project images on the hologram recording medium corresponding to the number of separations; and a reference beam optical system which projects a reference beam onto the hologram recording medium for interference with the image projected on the hologram recording medium.
The object beam optical system comprises spatial light modulation means for separately displaying a plurality of images in the parallax direction, a superposed projection optical system for superposing and projecting beams passing through this spatial light modulation means, and a beam-condensing projection optical system for converging a projected image from this superposed projection optical system onto a face of the hologram recording medium.
Consequently, the superposed projection optical system superposes beams passing through a plurality of images separately displayed in the parallax direction by the spatial light modulation means. The beam-condensing projection optical system converges the superposed projected images on a hologram recording medium""s face, enabling a plurality of element holograms to be exposed at a time.
Also, a holographic stereogram exposure method according to the present invention exposes 3-D image information onto a hologram recording medium, including: an object beam projection step for superposing and projecting light beams passing through a plurality of images separately displayed in a parallax direction and then condensing these beams to project images on the hologram recording medium corresponding to the number of separations; and a reference beam projection step for projecting a reference beam onto the hologram recording medium for interference with the object beam projected on the hologram recording medium by means of the object beam projection step.
The object beam projection step separately displays a plurality of images in the parallax direction, superposes and projects light beams passing through this separately displayed image, converges the projected image on the hologram recording medium surface in a parallax direction, and forms the projected image in a non-parallax direction.
Further, a holographic stereogram generation system according to the present invention records 3-D image information on a hologram recording medium and generates a holographic stereogram, including: an image generation system for generating a plurality of images in a parallax direction; an object beam optical system for separately displaying a plurality of images generated by the image generation system in a parallax direction, superposing, projecting, and converging beams passing through the plurality of separately displayed images, and projecting images corresponding to the number of separations on the hologram recording medium; and a reference beam optical system for projecting a reference beam on the hologram recording medium for interference with the image projected on the hologram recording medium by the object beam optical system.